Washington: In the first few days of his arrest, Mumbai terror attack accused David Headley refused to entertain any question on his childhood friend Tahawwur Husain Rana, as he wanted to save him.

It was only after he was informed by the FBI agents that Rana has been arrested on terror related charge that Headley agreed to respond to questions about Pakistani Canadian Rana, Headley informed a Chicago court during a recently concluded Rana trial.

"I did not want them to be affected by my case," the 50-year-old Pakistani American told the court when asked by the government attorney when he testified before the jury during the Rana trial.

"Besides your wife, who's the closest friend that you have in the world?" he was asked.

"Dr Rana," Headley said.

Headley said "Yes, I did" when the government attorney asked if he came to learn that Rana had been arrested.

And after Rana was arrested by the FBI on terror related charges, Headley said, he had conversation with the government about it.

After the conversation, the US attorney told Headley that if he was to cooperate it "would have to be complete," and he could not refuse to talk about any individual.

"So I decided to comply with that," he said.

The Mumbai terror accused also told the court that he initially lied about Rana to the FBI investigators, but later on provided information about him. The defence prosecutors however alleged that this was a ploy by the FBI to extract information from Headley about Rana.

The government, however, denied this allegation. Besides Rana, Headley also declined to answer questions about his wife.

"On the first few days, when you were asked questions about Mr Rana, what did you do?" Headley was asked. "I declined," he said.

"Besides declining, did you lie about Mr Rana when you were first interviewed?" he was asked.

"Yes" Headley responded.

"Did agents continue to ask you questions about Mr Rana?" he was asked.

"For a few days," Headley said.

"And at some point did you decline?" the US attorney asked.

"Yes," he said.

"Did you decline to answer any questions about any other individuals?" he was asked.

"Yes, my wife as well," Headley said.

While Headley was arrested on October 3, 2009, Rana was nabbed on October 18.